US3506472A - Pattern coating method - Google Patents

Description

R. A. LABOMBARDE ET AL 3,506,472

April 14, 1970 PATTERN COATING METHOD Original Filed Jan. 5, 1964 Sheets-Sheet 1 Omvm.

April 14, 1970 R. A. I ABOMBARD ET A1. 3,506,472

PATTERN COATING METHDD Original Filed Jan. 5, 1964 ,5 Sheets-Sheet -INVENTORS RAYMOND A-LABOMBARDE BY ERNEST J- DEWHURST 'PW' *Ream-.vw

ATTORNEYS April 14, 1970 R. A. LABOMBARDE ET AL 3,506,472

PATTERN COAT ING METHOD Original Filed Jan. 3, 1964 .5 Sheets-Sheet 3 BLANK TRAVEL Fi INVENToRs RAYMOND A. LABOMBARDE BYERNEST J.. DEWHURST pez 140.., 'f '79M ATTORNEYS PATTERN CIOATING METHOD .5 Sheets-Sheet 4 Original Filed Jan. 5, 1964 .Msg

April 14, 1970 R, A LABOMBARDE ET AL 3,506,472

PATTERN COATING METHOD ,5 Sheets-Sheet 5 Original Filed Jan. 5, 1964 United States Patent O 3,506,472 PATTERN COATING METHOD Raymond A. Labombarde, Nashua, N.H., and Ernest J. Dewhurst, Toronto, Ontario, Canada, assiguors, by direct and mesne assignments, to The International Paper Box Machine Company, Nashua, N.H., a corporation of New Hampshire Original application Jan. 3, 1964, Ser. No. 335,603, now Patent No. 3,313,270, dated Apr. 11, 1967. Divided and this application Mar. 10, 1967, Ser. N0. 641,077 Int. Cl. B44d 1/09, 5 00 U.S. Cl. 117-38 3 Claims ABSTRACT OF THE DISCLOSURE This application is a division of our application Ser. No. 335,603, filed Jan. 3, 1964, now U.S. Patent 3,313,270 of Apr. l1, 1967.

This invention relates to an apparatus and method for hot melt coating both the upper and the lower faces of a plurality of sheets in one pass through a machine and in a predetermined pattern.

In the paper box art, the production of wax, or other hot melt, coatings in a high gloss has become increasingly important and the spot, or pattern, application of such coatings has also become important.

It has been proposed to wax coat one, or both, faces of the cartons and then to remove the wax in certain areas, as a separate dewaxing step, in order to permit adhesive to be successfully applied to the carton for folding purposes. Needless to say dewaXing of this type is costly. It has also been proposed to use a pair of opposed wax applicator rolls, eachhaving a gravure surface with the desired pattern formed therein, but such rolls are expensive, change-over time is high and they are practical only for long runs on the particular size and pattern of blank for which they have been prepared.

Another expedient now in use in the trade is the provision of a hot wax fountain roll with an overall knurled surface, the roll transferring hot wax to a patterned pad on an applicator roll, and the pad transferring the desired pattern of wax to one face of the sheets, or blanks.

Such pads are usually heated or, if not, the pad soon becomes heated by contact with the hot wax and the life of the pads are therefore short, whether of rubber, neoprene or any other suitable resilient material. A serious disadvantage of resilient, hot wax applicator, pads become evident when it is necessary to spot, or pattern, Wax both the upper and lower faces of the sheets. In present machines, the opposed upper and lower applicator rolls form a nip and, when both rolls carry resilient, patterned, waX applicator pads, the relieved, or cutout, areas of one pad cause a failure to coat in the corresponding area of the other pad. It has thus proved necessary to traverse each cutout area with integral uncut strips, or to leave uncut spots throughout each cutout area, to provide suitable pressure in the area for achieving a proper coating on the opposite face of the sheets.

If each resilient, hot wax applicator pad were opposed by a solid smooth cylinder, rather than by a similar patice tern pad, proper pressure might be achieved but, in present machines, two passes would be necessary to coat both faces of the sheets and the pads would still be subject to rapid deterioration because of the heat of the hot melt coating.

It is the principal object of this invention to completely eliminate the resilient, hot wax applicator, pattern pad of the prior art and to provide a resilient pattern pad which remains cool, which is a backing pad rather than an applicator pad to avoid contacting hot wax and which produces the desired spot coating.

Another object of the invention is to provide apparatus for applying a pattern coating to both the upper and the lower faces of individual and successive sheets, in one pass-through a coating zone, with the pattern pads remaining cool at all times.

A further object of the invention is to provide an apparatus and method for high gloss wax coating of both faces of a plurality of sheets wherein the coating is applied in a pattern, remelted to a gloss on both faces and then chilled, or quenched on both faces all without damage, running or dripping of the coating.

Still another object of the invention is to provide a waxing apparatus and method which achieves the Iaccuracy and quality of rotogravure printing, achieves a rapid make-ready, and change of pattern pads and which achieves a long pad life, thereby substantially reducing cost while increasing the quality of the product.

A still further object of the invention is to provide a waxing machine of the pattern pad type in which the pads are quickly detachably rubber blankets and the backing rolls, which carry the blankets, are quickly accessible for changing over to a new run.

Other objects and advantages of the invention will be apparent from the claims, the description of the drawings and from the drawings in which:

FIG. 1 is a side elevation of a machine constructed in accordance with the invention,

FIG. 2 is a plan view of the machine shown in FIG. 1,

FIG. 3 is a diagrammatic, side elevation, on an enlarged scale of the pattern coating apparatus in the coating zone,

FIG. 4 is a fragmentary end view showing the wax overflow pipe of the upper applicator roll.

FIG. 5 is a diagrammatic side elevation on `a scale similar to FIGURE 3 of the heating means in the heating zone, and

FIG. 6 is a diagrammatic side elevation on a scale similar to FIGURES 3 and 4 of the chilling means in the chilling zone.

As shown in FIGURES l and 2, a coating machine 20 constructed in accordance with the invention includes the sheet feed zone 21, roll coating zone 22, heating zone 23, chilling zone 24 and stacking apron 25.

The sheet feeding means 26 in the sheet feed zone 21 may be of any well known type such as the timed top feed 27 with a register chain section 28, and having a one, two or three stream feed depending on the size of carton to be run. However, in this invention, the feeding means 26 is an integral assembly mounted on wheels such as 29 rollable on tracks 31 so that the entire feed may be moved rearwardly away from the coating zone 22 to enable an operative to have easy access to the rolls in the coating zone for make ready purposes. Marked timing gears 32 and 33 are provided to permit rolling the feeding means 26 out of, and back into, engagement without the necessity for retiming the machine.

The spot, or pattern coating mechanism in the coating zone 22 of the machine 20 includes iirst roll coating means 36 and second roll coating means 37, means 37 being close to means 36 and substantially identical thereto but inverted.

As best shown in FIGURE 3, first roll coating means 36 includes a first coating applicator roll 38, non-yieldably mounted for rotation in the bearings 39 and 40 fixed to the frame 41 of machine 20. The applicator roll 38 is of hard, unyieldable material such as steel.

The applicator roll 38 is provided with an overall precision engraved rotagravure surface 42 consisting of identical small pockets 43 and the roll is partially immersed in a coating supply pan 44. Roll 38 rotates in the direction of the arrow so that the wax, or other hot melt, coating picked up by the gravure surface 42, and metered by the doctor blade 45, will be carried upwardly into engagement with the underface 47 of each sheet 48 advancing along the paper line 49 of the machine.

First roll coating means 36 also includes the first backing, or blanket, roll 51, which forms the first pressure nip 52 with the gravure surface 42 of roll 38 and which is driven in the direction of the arrow. Backing roll 51 is journalled in bearings 53 and 54 and is resiliently and movably mounted, each bearing such as 54 being vertically slidable on a pair of posts 55 and 56 and resiliently pressed into pressure nip relationship by coil springs 57 and 58. The posts 55 and 56, of each bearing assembly, form part of an integral bearing block 59 supported on a rod 61 threaded in a frame member 62. Rod 61 carries a gear 63 meshed with a worm gear 64 mounted on a transverse shaft 65, whereby turning of shaft 65 raises or lowers both bearings 53 and 54 an equal amount. A calibrated dial 66 is associated with rod 65 so that turning of the rod 65 by hand crank 67 produces uniform precise, adjustment of the pinch of the rolls at first pressure nip 52.

The backing, or blanket, roll 51 is provided with an axially extending first row 70 of spaced, headed buttons 71 for receiving a corresponding row of keyhole shaped apertures 72 at one end 73 of the make ready blanket 74.

The blanket 74 is of resilient material such as rubber and is rolled, or wrapped round the cylindrical face of roll 51 until the row 75 of similar apertures at the other end 76 of the blanket is engaged on a second row 77 of spaced headed buttons 78. The row 77 is carried by an axially extending torsion rod 79, secured at the correct setting by a clamp 81, and lock screw 82 whereby removal of one pattern blanket and replacement with a blanket of different pattern is a matter of several minutes time only. The blanket roll 51 and blanket 74 are cool during operation of the machine but the roll 51 is hollow and provided with a hollow shaft 83 so that it can be connected into the heating system of the applicator rolls by valve 84, when the machine is not operating and it is desired to melt any inadvertent accumulation of the hot melt coating on the patterned surface of the blanket roll.

The second roll coating means 37, is substantially identical with the first roll coating means 36, but inverted so that the second coating applicator roll 85 is above the paperline 49 and forms a second pressure nip 86 with the second resilient pattern blanket 87 of the second backing, or blanket, roll 88, the latter being below the paperline 49. Preferably the rotagravure applicator rolls 38 and 85 are all over engraved, chrome plated, hollow steel cylinders and each roll is provided with a hollow shaft and rotary joint for the circulation of hot oil from the oil heating system 89 of the machine. Suitable thermostatic controls maintain the temperature of the applicator rolls at well above the melting point of the wax, or other hot melt coating composition, 91.

Preferably the first, or upper, backing roll S1 is vertically adjustable relative to the first, r lower, applicator roll 38, the latter being unyieldable. The second, or lower, backing roll 88 is vertically adjustable relative to the second, or upper, applicator roll 85, but unlike the first coating means 36, it is the applicator roll 85 that is spring loaded while the backing roll 88 is not spring loaded or resiliently mounted. To adjust for sheets of increased thickness, the first, or upper, blanket roll may be moved upwardly and the second, or lower, blanket roll may be moved downwardly.

The upper doctor blade 92, corresponding to doctor blade 45 not only meters the desired thickness of coating but also forms a fountain 93 in cooperation with the upper applicator roll 85. Hot wax is continuously pumped into the fountain 93, and into the supply pan 44 for the lower applicator roll 38 by a pump 94, from a sump 95, the pan being kept full and overflowing into the sump. An overflow wax return funnel 96 and 97 is mounted at each opposite end of the upper, or second, applicator roll to catch, and direct, excess wax from the fountain back into the sump 95. Each funnel such as 97 is spring mounted at 98 on the frame 41 of machine 20 and serves toavoid contamination or splashing of wax onto other parts of the machine.

The doctor blades 45 and 92 are each mounted on a pivoted arm such as 99, controlled by a set screw 101 so that light or heavy applications of the wax coating may be achieved as desired.

The blanket roll 88, is hollow and cool during operation but arranged to be heated to remove accumulations of wax, by connection to the valve 84.

All of the rolls of the first and second coating means are driven in the direction of the arrows by gears 102, 103, 104 and 105, on the same side of the machine, through a suitable speed reducer 106 and by the motor 107. The feed means 26 is driven by the same motor all in a manner well known in the trade and not necessary to describe herein. Similarly the hot oil heating system and the hot wax circulation system of machines of this type are well known and not necessary to describe in detail.

The first applicator roll 38 engages the underface 47 of each successive sheet, or blank 48, while the pattern blanket 74 of the first backing roll resiliently presses against the upper face 46 of the sheet to remove from the gravure surface 42 the measured amount of coating from the engraved pockets 43 and to apply the coating on the underface of the sheets. However, while blanket 74 is cool and does not contact the coating on the applicator roll, each relieved, or cutout, area such as 109 eliminates pressure on the sheet, and on the applicator roll, at the nip and results in a predetermined, dry, uncoated, area 110 on the underface of the sheet. It is these uncoated spots on which adhesive may later be applied to successfully fold the sheet into the desired carton. The first pressure nip 52 thus not only applies a pattern of the hot melt coating on the underface of each sheet, but also advances the sheet into the second pressure nip 86 for pattern coating of the upper face 46 of each sheet.

At the nip 86 the second applicator roll 85 deposits coating on the upper face 46 of each successive sheet while the second pattern blanket 87 resiliently presses on the underface 47 to create predetermined coated areas 1'11 and predetermined uncoated, dry areas 112. The sheets, or blanks, 48 thus emerge from the coating zone 22 with a pattern of coating on each opposite face thereof, in one pass through the machine and with no deterioration of the pattern rubber pads or blankets.

As best shown in FIGURE 5, the pattern coated sheets such as 114 are delivered by the second coating means 37 onto the upper stretch 115 of endless conveyor means 116 which supports and advances the sheets through the heating zone 23. Conveyor means 116 is preferably a plurality of endless chains of stainless steel such as 117 and 118, each trained around sprockets 119, 120 and 121, driven by a power train 122 from the motor 123 and reducer 124. A plurality of sharp pointed lugs, or pins, 125 are spaced around the chains and are in upstanding position along the upper stretch 115 whereby the pointed terminal tips 126 support the pattern coated underface of the sheets 114. Thus both the upper and lower pattern coated faces of the sheets, are exposed and may be heated to melt and glaze the coating without marking the underface of the sheets.

A section 127 of the conveyor means 116, about two feet in length, is upwardly pivotable on the` axes of the intermediate sprockets 136 so that an operative has access to the second blanket roll 87 for make ready purposes.

In addition, the upper stretch 115 is not entirely horizontal but includes a section which is arched upwardly in the centre a slight amount such as one or two inches, and supported on an arched track. Thus the sheets being advanced on the chains are first carried upwardly and then delivered in a downward sloping direction into the chilling zone.

The heating means 130, in the heating zone 23 is an infrared ray refractory type, gas iired burner 131, mounted at a spaced distance above the centre of the arched section of paper line 49 and arranged to remelt and liquefy the hot melt, patterned coating into a mirror-like, glossy pool with high gloss. The slight arching of the conveyor is not sufficient to cause the remelted coating to run, r drip, 0r to flow over the uncoated, dry patterned spots, but since the coating has been applied in a gravure pattern of small spaced dots, the dots are caused to flow toward each other to form a smooth coating. Preferably the heating means 130, also includes a second gas burner 132 similar to burner 131, but mounted at a spaced distance below paper line 49* to apply heat to the underfaces of the coated sheets if a glaze is desired on both faces. Vertical adjustment means 133, and horizontal adjustment means 134 are provided for adjusting the burners 131 and 132 and preferably burner 132 is located under the gap between the pivotable section and the arched section of the conveyor means 116.

The means 133 and 134, each include a fixed gear rack such as 163, a gear 164 meshed in the rack and a pawl, or dog, 165 for adjusting the height of the burner support 166 and the support 166 includes clamping bolts 167 for transversely adjusting the burner in the support.

The arched section of the conveyor means, indicated at 135 delivers the remelted sheets, or blanks, downwardly into the chilling zone 24 to uniformly chill the sheets without water back up thereby eliminating any tendency of Water marking. As shown in FIG. 6, the chilling means 138, in the chilling zone 24, includes a series of light, chrome plated steel cylinders, or rolls, such as 139 driven in the direction of the arrows and journalled in the sides of frame 41. The rolls 139 are driven by the gear train 141 through a power train 142 by the reducer 124 and serve to tangentially engage the pattern coated underfaces of the sheets while advancing the sheets individually and successively through the chill zone 24 to the stacker apron 25. In addition, the rolls 139 are partially immersed in a water pan 152 and constitute applicators for applying a film of the coolant water to the under coatings to quench and harden the pattern coating.

The chilling means 138 also includes a series of about five water fall, or head, boxes such as 143 and 144, each spaced above the paper line 49 and arranged to discharge a low, unbroken, liquid curtain on the upper coated faces of the sheets advancing therebelow. A suitable high volume centrifugal pump 145 maintains water circulation from the water tank 146 to the water pan 152 and to each of the water boxes 143 and 144 and a pair of driven, wringer rolls 147 and 148 are positioned at the end of the chill zone 24 to dry and deliver the sheets to the apron 25. A separate pump 149 integral with the water chilling unit 150 maintains the water in the water tank 146 at the required temperature.

The water Ibox 143 includes a partition 151 for trapping any sediment, and a transverse sloping curtain member 153 for guiding the water `downwardly and forwardly in an unbroken, liquid curtain to fall on the sheets advancing downwardly and forwardly thereunder. Thus the water cannot back up the sheet to create water marks and the coatings are instantly quenched, hardened and chilled. The remaining boxes 144 continue to quench, harden and 6 chill the coating as the sheets advance through the machine at a speed of about 400 feet per minute.

The water boxes 144 are of known type and shown in U.S. Patent 3,070,457 to Labombarde of Dec. 25, 1962 but in this invention, they are reversed with the water cascading in a uniform sheet toward the oncoming blanks. The water box 143, however, provides the instantaneous quenching effect desirable for hardening the glossy wax coatings, with the unbroken, continuous transverse sheet of liquid coolant gently falling in the direction of advance of the blanks to eliminate any undesirable water marks. Because of the relatively long cascading flow of the coolant down the slope 154 of member 153, splitting of the stream by foreign particles is avoided and any such split tends to eliminate itself before reaching the arcuate shelf 155.

While the apparatus of the invention is especially useful with hot coatings, it will lbe understood that water soluble compositions may also be platten?, coated by the apparatus, in which case the applicator rolls 38 and 85 are cool, at ambient temperatures, rather than heated. Similarly, while a resilient surface, or resilient blanket 74 or 87, is preferred on the backing rolls, a yieldable material such 'as felt may sometimes give satisfactory results and is intended to be included within the scope of the invention.

We claim:

1. The method of pattern wax coating a plurality of sheets on the upper and lower faces thereof by means of upper and lower hot wax applicator rolls having overall gravure surfaces each forming a nip with lower or upper resilient faced backing rolls having relieved areas therein, said method comprising the steps of:

passing said sheets individu'ally and successively in timed relation along a path over said lower, hot wax application roll and coating the lower faces thereof while said upper backing roll is resiliently pressing on the upper faces thereof except in said relieved areas where no coating is desired, and

passing said sheets individually and successively, still in timed relation further along said path, under said upper, hot wax applicator rolls and coating the upper faces thereof while -said lower backing roll is resiliently pressing on the lower faces thereof except in said relieved areas where no coating is desired.

2. A method as specified in claim 1 plus the additional steps of advancing said sheets, subsequent to said coating on both faces, individually and successively further along said path while supporting the same on a plurality of spaced pin point areas;

and exposing said coating on the upper faces of said sheets, while so pin supported and while advancing upwardly on a slight incline to heat suicient to reliquefy and glaze said coating.

3. A method as specified in claim 2 plus the additional steps of still further advancing said sheets individually and successively along said path while roll supporting the same through a cooling bath while simultaneously showering cooling liquid on said sheets from a series of spaced, low, sheet-like waterfalls.

References Cited UNITED STATES PATENTS 3,257,226 6/ 1966 Thwaites 118-249 3,120,449 v2/ 1964 Griswold 117-38 3,070,45 7 l2/ 1962 Labombarde 118-227 2,396,946y 3/ 1946 Grupe 117--38 ALFRED L. LEAVI'IT, Primary Examiner M. F. ESPOSITO, Assistant Examiner U.S. Cl. X.R. 117-64, 68, lll

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